Behind-the-ear hearing aids are known which comprise a curved, hook-shaped shell running substantially along an identically shaped hearing-aid axis and containing acoustic-electric transducers, electric-acoustic transducers and electronics. One shell end, usually the tapering end, constitutes the acoustic output device to the ear.
Such behind-the-ear hearing aids include a compartment to hold an ordinary or rechargeable battery. Such hearing aids use a button cell that is an ordinary or rechargeable battery. An axis of the battery is transverse to the above-mentioned axis of the hearing-aid shell. The design includes a hinging lid for the hearing-aid shell and retaining means for the cylindrical battery case that are arranged such that the latter""s cylinder axis runs parallel to the pivot axis of the hinging lid. This configuration has several drawbacks.
Because the cylindrical case of the battery is transverse to the longitudinal axis of the curved, hook-shaped hearing-aid shell, the battery case wastes a relatively substantial space within the hearing aid. Moreover, there are mold parting lines between the hinging lid and the hearing-aid shell that run essentially along generatrices of the curved, hook-shaped hearing-aid shell. At least some of these parting lines will rest directly against the user""s skin when in operation. Therefore, the parting lines constitute a comparatively elongated, critical site through which perspiration, humidity etc. may enter the battery compartment.
The present invention is directed toward eliminating or reducing the aforementioned drawbacks. According to the present invention, the battery compartment is situated at the shell end opposite the acoustic output device. The battery compartment is configured to receive a cylindrical rechargeable or ordinary battery case such that the cylinder axis of the battery compartment runs substantially coaxially with the hearing-aid longitudinal axis. Accordingly, an optimally minimal receiving volume or space is needed for the ordinary or rechargeable battery on account of the substantially cylindrical cross-section, in particular the inside cross-section of the hearing-aid shell, because the battery case now can be inserted coaxially with the hearing-aid tubular axis and in practice flush with the shell wall.
In a preferred embodiment of the invention, the above cited compartment comprises a first, preferably resilient, preferably central electric terminal, preferably also coaxial with the hearing aid""s longitudinal axis, and at least one second electric terminal in the region of the erect compartment wall.
Even though merely two electric terminals suffice to contact a battery placed in the compartment, it may be advantageous in some circumstances to use more than two terminals in the compartment as regards another preferred embodiment of the hearing aid of the invention. The battery compartment of the hearing-aid shell, instead of holding an ordinary battery or a rechargeable battery, may receive the plug-in element of an attachment module, or an add-on module, to make electrical contact with at least two or more electric terminals. As regards the attachment module, which in this design includes the actual battery compartment at the hearing aid shell, it comprises a compartment at least substantially identical with the above mentioned compartment in the hearing-aid shell. In this manner, the module can be plugged into the battery compartment of the hearing-aid shell and the electric power then is supplied to the hearing aid by a cylindrical ordinary or rechargeable battery placed in the attachment-module compartment.
In this design, of course, more than one attachment module may be connected to the actual hearing-aid shell so as to practically extend the hook-shaped hearing-aid shell.
Whether the compartment is situated in the hearing-aid shell or, as mentioned above, is in an attachment module, it is furthermore fitted with a lid. The lid, in its closed position, is substantially perpendicular to the longitudinal axis of the hearing aid and preferably can be locked only by using a tool. This feature assures safety. For instance, when the hearing aid is used by children: lacking a tool, for instance a screwdriver, it will be impossible to remove the ordinary or rechargeable battery from the hearing aid.
The cited lid is of modular design and preferably can be removed in non-destructive manner from the hearing-aid shell. For example, after the lid has been removed, the lid can be reused on the hearing-aid compartment or used on the compartment of an attachment module.
Furthermore a code, for instance a color code, may be mounted on behind-the-ear hearing aids, to identify which ear, left or right, is to be fitted with the particular hearing aid.
In order to avoid fixed coding during the manufacture of comparatively complex parts, the invention proposes furthermore that the above mentioned lid be fitted with a left/right ear code, preferably located on an externally visible part of a lock mounted on the lid. In this manner all lids can be manufactured identically and externally coded parts, for instance coded in red or blue, will only be inserted during the assembly of a simple lock.
In an especially preferred embodiment of the hearing aid of the invention, an add-on module or a further add-on module with a plug-in element is inserted in the aforementioned compartment, in the hearing-aid shell or in that of an add-on module. The add-on module preferably encloses a rechargeable battery.
In a highly preferred embodiment, the rechargeable battery is a lithium battery in which the energy density is advantageously higher than that of other rechargeable batteries especially as regards the hearing-aid application. The preferably encapsulated unit of rechargeable battery and add-on module also preferably is fitted with a charging regulator. The charging regulator precedes the rechargeable battery on the input side and preferably includes an inductive charging input. The charging power is applied as desired through a transformer and without externally accessible and damage-susceptible rechargeable-battery terminals. In particular when a Li-ion rechargeable battery is used in such preferred manner, its effective voltage will be matched to requirements of the electronics following the hearing aid by a voltage regulator on the output side of the add-on module.
Basically it is highly advantageous to use a Li-ion rechargeable battery as the electric power source for a hearing aid, whether of the behind-the-ear or the in-ear type, and to exploit the properties of this kind of battery which are most advantageous with respect to hearing aids.
In accordance with further aspects of the invention, a number of substantial advantages regarding compactness, ease of maintenance and long life are offered compared to using other kinds of batteries.
The present invention provides a behind-the-ear hearing aid of modular design and having a hook-shaped shell fitted at one of its ends with a receiving compartment fitted with at least two accessible electrical terminals. A module""s plug-in element is insertable into the receiving compartment, and the module, in turn, has its own compartment substantially identical with the aforementioned one in the hearing-aid shell. Leaving aside the question of how and where an ordinary battery, or a rechargeable one, is stored in the behind-the-ear hearing aid, it is intrinsically highly advantageous to situate the cited receiving compartment in the hearing aid to selectively allow correspondingly designed attachment modules to be mounted on the same basic hearing-aid configuration.
An attachment module of the invention for a hearing aid of the above kind comprises a plug-in element preferably subtending a substantially cylindrical external surface, a receiving compartment situated at the module and opposite the plug-in element to receive an element substantially shaped like the plug-in element and which can be locked by a preferably detachable, preferably tool-lockable lid. The attachment module preferably is in the form of modules for a wireless communication interface or a plug adapter module to adapt the hearing aid for further acoustic/electric transducers, a rechargeable-battery module which typically is larger than conventionally used ordinary batteries, a programming module or a mechanical drive module.
A further attachment module for the hearing aid consists of a first portion having a an external cross-sectional contour substantially corresponding to the external cross-sectional contour of the hearing aid, and a second portion of a comparatively lesser diameter, and a rechargeable battery. Preferably, this attachment module is encapsulated per se and, contrary to the module cited before, does not include its own compartment. Preferably, the rechargeable battery is integrated into the first, thicker portion, to be followed by a voltage regulator in the second, thinner plug portion. Moreover, a storage-battery charging regulator is preferably present in the first above cited portion and is preferably connected at the input side with an inductive pickup to be able to feed the charging power using a transformer, that is, being free of externally accessible terminals.
In a preferred embodiment and on account of the reasons given above, the rechargeable battery present in this attachment module preferably is a Li-ion battery.